glFragmentMaterial(3G) OpenGL Reference glFragmentMaterial(3G)
glFragmentMaterialfSGIX, glFragmentMaterialiSGIX,
glFragmentMaterialfvSGIX, glFragmentMaterialivSGIX - specify fragment
material parameters for the fragment lighting model
void glFragmentMaterialfSGIX( GLenum face,
GLenum pname,
GLfloat param )
void glFragmentMaterialiSGIX( GLenum face,
GLenum pname,
GLint param )
face Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname Specifies the single-valued fragment material parameter of the
face or faces that is being updated. Must be GL_SHININESS.
param Specifies the value that parameter GL_SHININESS will be set to.
void glFragmentMaterialfvSGIX( GLenum face,
GLenum pname,
const GLfloat *params )
void glFragmentMaterialivSGIX( GLenum face,
GLenum pname,
const GLint *params )
face Specifies which face or faces are being updated. Must be one of
GL_FRONT, GL_BACK, or GL_FRONT_AND_BACK.
pname
Specifies the fragment material parameter of the face or faces that
is being updated. Must be one of GL_AMBIENT, GL_DIFFUSE,
GL_SPECULAR, GL_EMISSION, GL_SHININESS, GL_AMBIENT_AND_DIFFUSE, or
GL_COLOR_INDEXES.
params
Specifies a pointer to the value or values that pname will be set
to.
glFragmentMaterial assigns values to fragment material parameters. There
are two matched sets of fragment material parameters. One, the front-
facing set, is used to shade points, lines, bitmaps, and all polygons
(when two-sided lighting is disabled), or just front-facing polygons
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glFragmentMaterial(3G) OpenGL Reference glFragmentMaterial(3G)
(when two-sided lighting is enabled). The other set, back-facing, is
used to shade back-facing polygons only when two-sided lighting is
enabled. Refer to the glFragmentLightModel reference page for details
concerning one- and two-sided lighting calculations.
glFragmentMaterial takes three arguments. The first, face, specifies
whether the GL_FRONT fragment materials, the GL_BACK fragment materials,
or both GL_FRONT_AND_BACK fragment materials will be modified. The
second, pname, specifies which of several parameters in one or both sets
will be modified. The third, params, specifies what value or values will
be assigned to the specified parameter.
Fragment material parameters are used in the lighting equation that is
optionally applied to each fragment. The equation is discussed in the
glFragmentLightModel reference page. The parameters that can be
specified using glFragmentMaterial, and their interpretations by the
lighting equation, are as follows:
GL_AMBIENT params contains four integer or floating-point values
that specify the ambient RGBA reflectance of the
fragment material. Integer values are mapped
linearly such that the most positive representable
value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped. The initial
ambient reflectance for both front- and back-facing
fragment materials is (0.2, 0.2, 0.2, 1.0).
GL_DIFFUSE params contains four integer or floating-point values
that specify the diffuse RGBA reflectance of the
fragment material. Integer values are mapped
linearly such that the most positive representable
value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped. The initial
diffuse reflectance for both front- and back-facing
fragment materials is (0.8, 0.8, 0.8, 1.0).
GL_SPECULAR params contains four integer or floating-point values
that specify the specular RGBA reflectance of the
fragment material. Integer values are mapped
linearly such that the most positive representable
value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped. The initial
specular reflectance for both front- and back-facing
fragment materials is (0, 0, 0, 1).
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glFragmentMaterial(3G) OpenGL Reference glFragmentMaterial(3G)
GL_EMISSION params contains four integer or floating-point values
that specify the RGBA emitted light intensity of the
fragment material. Integer values are mapped
linearly such that the most positive representable
value maps to 1.0, and the most negative
representable value maps to -1.0. Floating-point
values are mapped directly. Neither integer nor
floating-point values are clamped. The initial
emission intensity for both front- and back-facing
fragment materials is (0, 0, 0, 1).
GL_SHININESS params is a single integer or floating-point value
that specifies the RGBA specular exponent of the
fragment material. Integer and floating-point values
are mapped directly. Only values in the range
[0,128] are accepted. The initial specular exponent
for both front- and back-facing fragment materials is
0.
GL_AMBIENT_AND_DIFFUSE [Toc] [Back]
Equivalent to calling glFragmentMaterial twice with
the same parameter values, once with GL_AMBIENT and
once with GL_DIFFUSE.
GL_COLOR_INDEXES params contains three integer or floating-point
values specifying the color indices for ambient,
diffuse, and specular lighting. These three values,
and GL_SHININESS, are the only fragment material
values used by the color index mode lighting
equation. Refer to the glFragmentLightModel
reference page for a discussion of color index
lighting.
The fragment material parameters can be updated at any time. In
particular, glFragmentMaterial can be called between a call to glBegin
and the corresponding call to glEnd.
While the ambient, diffuse, specular and emission fragment material
parameters all have alpha components, only the diffuse alpha component is
used in the lighting computation.
GL_INVALID_ENUM is generated if either face or pname is not an accepted
value.
GL_INVALID_VALUE is generated if a specular exponent outside the range
[0,128] is specified.
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glFragmentMaterial(3G) OpenGL Reference glFragmentMaterial(3G)
ASSOCIATED GETS
glGetFragmentMaterial
MACHINE DEPENDENCIES
The SGIX_fragment_lighting extension is supported only on Octane2 VPro
systems.
glFragmentColorMaterial, glFragmentLight, glFragmentLightModel
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